docs: def save(self, filepath):
          """Save current configuration to file.
  
          :param str filepath: Path to file where settings will be saved.
          :raises: ValueError if supplied filepath cannot be written to.
          """
          self._config.add_section("RetryPolicy")
          self._config.set("RetryPolicy", "retries", str(self.retry_policy.retries))
          self._config.set("RetryPolicy", "backoff_factor",
                           str(self.retry_policy.backoff_factor))
          self._config.set("RetryPolicy", "max_backoff",
                           str(self.retry_policy.max_backoff))
          super(RequestHTTPSenderConfiguration, self).save(filepath)